1. Field of the Invention
This invention relates generally to a flotation barrier or boom, and, more particularly, to an improved contamination control boom of the type which is collapsible for more compact storage, and which has improved heat resistance properties, making the boom able to contain a burning surface contaminant for long periods.
2. Description of Related Art
The increasing frequency of contamination of bodies of water such as harbors, rivers, lakes, oceans, and the like, by spills of contaminants, e.g. petroleum, petroleum products, or other chemicals, has increased the need for effective contaminant containment and disposal equipment. Particularly, containment barriers or booms are utilized to separate the area of a body of water having a contaminant on the surface thereof from adjacent areas of the body of water. Typically such booms comprise a flotation portion to provide buoyancy, which rises above the surface of the water, and a weighted curtain or skirt portion which extends down into the water to a distance effective to prevent contaminants from escaping underneath the flotation portion of the boom.
Because such booms are necessarily relatively long, and are desirably stored so as to be quickly deployable in the area of a contaminant spill, it is advantageous to provide a boom which is collapsible, so that a smaller volume of space is required for storage, and so that it is more easily transported. However, the boom should be capable of quickly being put in service, and it has been found that storing such a containment boom in a collapsed condition wound on a reel or drum, and having the ability to spring quickly to its intended shape when free of the storage reel, satisfies these conditions. In order to do so, the boom should be made flexible for storage, and yet, the boom structure must be adequately stiff and damage resistant to function properly when deployed.
A further desired attribute is that the boom be fire resistant. It is often the case that a flammable contaminant is to be contained, or that such a contaminant is purposely burned when contained. For example, in-situ burning of spilled petroleum is recognized as a desirable clean-up response, as the harmful effects of the emissions of the products of combustion are thought to be much less damaging to the environment than the effects of spilled oil contaminating shoreline, sea floor, and wildlife.
Consequently, the boom must be constructed so as to be able to perform its containment function while withstanding the high temperatures associated with burning of contaminants for extended periods, which may last several days. Certain woven ceramic fiber materials have a sufficiently refractory nature that their physical properties will remain unchanged under such conditions, and are sufficiently flexible to form an outer skin of the boom. However, such materials may be somewhat porous, or may be punctured, and thus not be suited to containing air to provide flotation.
It has been recognized by those concerned with the art that a separate float, which is capable of maintaining the buoyancy of the boom independently of the porosity of the outer layer or layers of the material from which the boom is constructed, is a solution to this problem. Conventionally, this is done by placing float material, such as a closed-cell foam material, within the float portion of the boom.
Conventional float materials such as closed-cell foams may be relatively stiff, and therefore unsuited to the bending inherent in compact storage, deployment and use of a boom of this type. Further, conventional closed-cell foams otherwise suitable for this application will break down at temperatures to which they may be required to be exposed for long periods in a containment boom application for burning surface contaminants. Some present devices employ a flotation material having refractory properties. However, such relatively refractory materials tend to be more stiff in comparison to conventional float materials such as foams formed from polymeric resins having otherwise similar closed-cell characteristics. Consequently, booms using such refractory flotation materials are relatively heavy and more difficult to store compactly, as the flotation portions of such booms do not deform as readily.
Another consideration in the design of booms is that they must be constructed so as to remain functional in adverse conditions such as rough water surface conditions or a very rapid deployment in an emergency. Again, flexibility and light weight are important factors in allowing the boom to function as required. Yet high strength requirements of materials employed conventionally also implies a stiffer overall construction, and hence presents a dilemma to those concerned with providing a serviceable boom construction which is compactly storable.
Similarly, it has been recognized that providing a flexible float within the boom is desirable, yet conflicts with the requirement that the boom be capable of functioning in the very high temperatures that may be associated with containing a burning surface contaminant over a long period of time. Conventional float materials must be somehow shielded from heat that may damage them, implying further structure adding bulk and/or stiffness, or the use of refractory float materials requiring less protection that are themselves more stiff.
In light of the forgoing, it has been recognized that the desirable attributes of a contaminant containment boom of this type should include suitable containment capability even when exposed to the intense heat of burning contaminants such as spilled crude oil, for example. Also desirable are flexibility and durability for ease of deployment and use, even for long periods, and collapsibility and flexibility for more convenient storage and transport. Convenience of storage and transport allows the boom to be more accessibly located in relation to potential contaminant sources, thus giving rise to the potential to reduce the damaging effects of a spill.
These attributes being recognized, those skilled in the art will appreciate that the design of containment booms is difficult because of the often conflicting requirements placed on materials used. What is needed is a containment boom with durable, flexible, buoyant, heat resistant, flotation that is at once flexible and collapsible for convenient storage, transport, deployment and use, and also ruggedly constructed so as to reliably survive adverse conditions of use without loss of function. The present invention addresses these concerns.